


Precious

by SXH1417



Category: Undertale (Video Game)
Genre: A little bit of blood, Biting, Breeding Kink, Claiming, Clawing, Come Inflation, Cunnilingus, Dubious Consent, How did i forget breeding kink?, Little bit of Guilt, M/M, Mating Cycles/In Heat, Somnophilia, Tiny Angst, Virginity Kink
Language: English
Status: Completed
Published: 2019-01-16
Updated: 2019-01-16
Packaged: 2019-10-11 10:10:30
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,750
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17444903
Author URL: https://archiveofourown.org/users/SXH1417/pseuds/SXH1417
Summary: Sans really should have locked his bedroom door. He was too trusting, especially with Blood. When Blood sees him, he just itched to touch.





	Precious

**Author's Note:**

> I've been meaning to post this fic up for a long time. I just never finished it until recently, thanks to Twitter Poll I did. I hope you all enjoy!

Stars, this wasn't fair. It wasn't fair that he was so pretty and cute. No marks on his bones where his own was marred. It wasn't fair how small and fragile he looked. It certainly wasn’t fair that he could sleep like the dead. So peaceful, like he didn’t have a care in the world. Sans was just so... trusting.

It was strange how Sans trusted him and his brother so unconditionally. He didn't show fear at all when they first arrived. He and Papyrus had shown them nothing but trust and care for their wellbeings. It was a nice change from his own universe. It didn’t have that crazed edge behind the well meanings.

Seeing those lazy eyelights light up every single time Blood tried to joke like he used to. On top of that, he showed so much care for Sugar, even going as far as fixing his brother's teeth to help boost his confidence. When he got started talking about science and stars his eyes always held a fondness and a happiness that he hadn't seen in the mirror in a very long time.

He was pure, sweet, funny, kind, and his smile... it was absolute perfection. He just wanted to press a kiss to those teeth and leave him breathless. He wanted to touch those pristine bones. Blood wanted to do so many things with him.

Now he had a chance to do it. Sans had taken some sleeping medicine tonight with his dinner. He'd taken more than normal, no doubt to keep the nightmares away, so Blood could lift up his arm and drop it and the other wouldn't stir.

He was horrible for breaking Sans's trust like this. He was dirt, trash, a horrid excuse for a monster. But, he itched so bad to touch those bones, to taste that pretty blue magic. Heh... he must be pretty narcissi- _sick_ to even consider doing this.

Nonetheless, he began by peeling Sans's jacket back. Then he pushed up the smaller's shirt to show those ivory ribs. They were so small and beautiful. He ran his phalanges over them, letting them catch on each and every one. They were as smooth as they looked but so small that they were barely the width of his finger. He massaged them softly admiring the little sighs it drew out of his smaller alternate.

Stars he shouldn't be this cute.

Blood groaned lowly as he continued to pet and grope Sans's body. He made the most delicious sounds when Blood's hands grasped wandered down at his lumbar vertebrae and his ilium. His iliac crests were sensitive. Sans’s breath would hitch slightly at the barest graze.

Then a loud moan broke through the air as Blood grazed against Sans's pubic symphysis. He stopped for fear the other had woken up. Leaning back, he found it hard to resist continuing when Sans squirmed against the sheets in his slumber, still blissfully unaware of what Blood was doing to him... and what he was doing to Blood.

Blood nearly moaned just as loudly. His erection was pressing hard against his shorts. He needed Sans. He needed him _badly._

Licking his teeth, Blood slowly pulled down Sans's shorts to expose those sweet bones. He took the public symphysis between his fingers, shivering as the other's breath hitched. Gently, he began to massage the cartilage. Sans's body really began to twitch and writhe then. Magic made its way down to his pelvis, shifting erratically. With his fingers in the way, the magic couldn't form, so it clung to his phalanges and up to his metacarpals. And they clung tight.

Blood could only manage to move his hand so much with the way Sans's magic wound around it. He looked down and took joy in watching the way the magic quiver and loosen or tighten or just squirm like Sans's body when he used different pressures on the sensitive point or switch to rubbing it. A deep massage of the area had Sans nearly thrusting up into the contact, crying out a little too loudly. The magic would jump in tandem.

Sans's breath soon quickened, signaling to Blood just how close he was. Blood gently ease off until he pried his fingers off completely. The tendrils of magic that clung to him tightened a little as he pulled away. He managed to free his hand, allowing the magic to quiver and then solidify into a set of very wet, plump lips and a cute little clit that begged for attention.

Blood growled lowly at the sight. It was everything he hoped for and more. The color was so pretty. His own magic could never have been as pretty as this. The slick little lips were wet, almost dripping from the attention Blood had given him. He groaned as he leaned in, pulling Sans’s legs apart in the process. His tongue snuck out of his mouth. He needed a taste of this.

The first drag of his tongue had him grinding into the mattress and Sans wiggling desperately. The second was followed by a third and then Blood’s mouth being practically attached to it. He enclosed his mouth around the small organ, lapping at the folds, teasing the labia. He let a little nip at Sans’s clit and heard a small cry from him.

Blood grinned. He needed to hear more of those noises. Oh, it would be such a wonderful day when Sans laid under him, panting and moaning his name, crying out for more as played with his small bones. Sans would beg him to fuck him. He would whine and cry for it with pretty blue tears. He would love ever second of Blood’s cock sliding into him, taking him completely like the good pet he was. Then he would beg for it harder, faster more, to fill him up, to knot him.

Blood barely registered the fact that Sans was close again. He had nearly gotten lost in his fantasy to the point that he’d almost let Sans cum. No, no no. Not yet. he needed to play with him some more. He left Sans alone for a minute to let him cool off. It was cute to watch him get frustrated in his sleep. Squirming and squeezing his femurs together to get some sort of friction was so sexy.

He didn’t expect for Sans to actually reach down with his own fingers and play with himself. His little fingers danced across his folds, rubbing harshly. He was too slick to find any real friction. His little nub never truly getting the attention it needed, despite Sans’s unconscious attempts. Blood practically drooled at the sight.

Taking Sans’s wrist into hand, he pulled it away. It stayed at Sans’s side, but he continued to squirm. Blood dove back down between his legs and began to slip his tongue between Sans’s folds. He circled it around the hole a couple of times before diving in.

Blood dipped his tongue inside Sans, tasting everything he had to offer. The magic there had a sweet tanginess to it. Tart. Sans tasted like that type of candy that was sweet and then sour. Blood loved it. He couldn’t get deep enough. Even as his nasal aperture was flush against Sans’s clit, he just wasn’t close enough. He wasn’t deep enough.

 Hand was grasping at his skull, pawing softly. The cries and whimpers that fell out of Sans’s mouth were almost as delicious as his pussy.

Blood hummed into Sans as that hand felt like it was petting him, encouraging him, until it grabbed the edge of his broken skull, He had to keep his jaw from snapping shit on the poor little guy. It was a strange sensation having someone else’s fingers inside his skull. Not unpleasant, just… strange. It sent tiny jolts along the edges of the bone. It made Blood pause as a tingling warm began to spread through his skull.

The grip tightened down a little as Sans ground his cunt against Blood’s teeth, forcing him to snap back to attention. Blood’s arousal heightened at the action.

Fuuuuuuck. That was hot. Yes. He liked this. he approved. He hoped that Sans did this more often. It would feel amazing and be oh so sexy to have Sans sitting on his face and do that, begging for more, squirming for his attention.

Blood gave those soft lips a few last laps before giving the clit a small nip. He gently pried Sans’s hand off his skull. He let go without a fight, but with a small groan of protest.

Blood pushed down his shorts, freeing his cock. It ached to be buried inside those soft walls. The barbs pulsed in need as he lined his cock up. He ground against those wet folds with a not so quiet moan. It felt good. Sans was completely soaked. It didn’t take much more than a couple thrusts to lube up his cock with Sans’s juices. The smaller skeleton’s hips wiggled a little from the simulation, twitching in need. Oh how Blood was ready to give.

He lined himself up again, then slowly, painfully so, began to push inside. He felt a small give as he did, followed by a loud whimper. He paused, looking down to find Sans’s pussy now leaking red magic.

“shit, precious, am I yer first? daw… you should have told me…” he chuckled, leaning forward to press little kisses to San’s face as he adjusted to the size. He was such a fucking creep, he knew. Sansy really should have locked his door. He caressed Sans’s legs and rubbed his little clit to help him along.

Once he was ready, Blood continued. He pushed in all the way to the hilt. He moaned at the feeling. Sans felt perfect like he was made for Blood. Sliding inside felt like two pieces sliding together, perfect for each other. Fuck, Blood was already panting. His body felt almost unbearably hot now. He hoped Sans’s body could handle how rough he got.

Squirming again, Sans clearly had enough of waiting. Blood leaned over his little body, putting one hand next to his head while the other held his hip. Like this, Blood began rocking into Sans. He would pull out only a fraction before he thrust back in, adding more and more. The noises that escaped Sans’s teeth grew in number and volume as time went on, as Blood continued to pull out more and more with each thrust.

The mattress was rocking with their movements. The springs squeaked under them. Both of those noises could be heard loudly over both Sans and Blood.

Shit… shit, shit, shit. Blood really was doing this. He was fucking Sans while he slept. Growling, Blood moved both hands to Sans’s femurs. He spread them wider, holding them in the air. He snarled into Sans’s cervical vertebrae, drawing a shivering whine out of him.

“yer so fucking beautiful, precious… fuck… hah… ah… yer so fucking sexy…” Blood growled, pulling out halfway and thrusting in hard. “i want you to feel this in the mornin’. want you to feel me… every last bit of me… hah… uh… Ah…”

Blood couldn’t help moaning into Sans’s neck. Those velvety walls were just sucking him back in with every movement. He could feel every part of his cock getting attention as those walls twitched and squeezed him just right. His barbs wanted to bury inside him deeper, make Blood cum. Make him cum inside.

Blood began to rut faster, wanting just that. He needed to cum inside his precious. His soft little Sans. His. His… All _his._

“Mine… hah… yer mine, Sansy… my mate… mine… fuck, fuck, fuck!”

The walls squeezed him tighter with every word. He rolled his hips, finding that perfect angle for Sans before brutalizing it. He pounded into him, knowing without a doubt Sans would feel this in the morning. He would wake up to Blood’s cum leaking out of him, marking him.

Sans was moaning and crying out in bliss. He was clutching the sheets. Little tears started pricking at the corners of his sockets. His cries got louder and louder until he practically shouted under Blood. His walls clamped down on his cock, nearly stopping it from moving. Blood cursed loudly one more time before he pushed as far as he could. The barbs swelled and hardened, not enough to hurt though, and Blood was cumming. He was cumming inside Sans’s pretty blue cunt.

He was still rocking his hips, watching all his cum fill his little mate.

“Come on… take it… take it...” he growled. Sans’s body formed a womb not a second later to take the overflow. Blood purred at the sight. Sans’s blue stomach formed, not really concealing the red magic’s travel deeper inside. Blood rubbed the magic lovingly. “fuck yes… take it all, precious… take it all… my little momma gonna be bred up so well… fuck… you look so good like this, Sansy… ta take all of me so fucking well…”

The sight alone was all it took to get Blood itching to move again. He wasn’t done. Not in the least bit. Sans’s stomach all round with magic, that blood red color was clearly seen through the blue. His cock twitched. Desire urged him to move again. “damn it, precious… i need to breed you proper.”

With this, his barbs softened enough to move again. Blood wasted no time at all. He turned Sans onto his front and hiked him up onto his knees. He couldn’t see his handiwork from this position, but it was the best way to keep all his cum inside.

 

* * *

 

 

Sans didn’t know how much longer he could last through this. Blood had been fucking him non-stop for hours. His stomach felt so full… he could feel it all moving inside him.

He’d woken up to Blood eating him out, going to town like he’d owned it. He had no idea that had actually been his intention. Then again… the steady smell of musk and pine had grown stronger the longer he’d let this go on. There was no doubt in Sans’s mind that this was the first heat Blood has had in a long, long time. Who was Sans not to help?

However, when Blood thrust inside, he hadn’t expected to tear. Blood was so big. It had been hard to pretend to be asleep through the pain. It had been even harder for the thorough fucking he had gotten afterward.

Now that he was facing away from Blood, he could let loose a little more. His eyes were mostly lidded, little hearts in them as Blood clawed at his bones, marking him up even more. Stars, they really had a lot of the same kinks when in heat.

This particular position was one of Sans’s favorites in his fantasies. Clutching a pillow while face first in the bed, hips raised as he got pounded into oblivion. His lover draped over his back, clawing at his ribs, groping him, taking what they wanted as they bit down on the marking spot. Blood must be somewhat conscious of what he was doing. He bit the pillow instead of Sans, but the proximity alone had Sans tensing in orgasm again.

Blood followed soon after, pulling Sans down with him as he collapsed to his side. The barbs dug a little at the movement.

Was it over? He wondered as the sun began to peek a few rays into his window. A slow humping started up again, telling Sans otherwise. When Sans heard a soft whine, he grew a little concerned. He turned his head a bit. Blood seemed to be in pain. The look in his eyelights told him that his heat finally calmed down enough for him to gather his senses.

Blood quickly buried his face into Sans’s back, hugging him close. Sans pet his arm. His voice was a little hoarse, but Sans could hear the apologies clear enough.

“…I’m sorry… I didn’t mean to… I’m sorry…” Blood said. Sand sighed and petted his arms and his skull.

“it’s okay… it’s not your fault… it’s okay…” Sans replied with a rasp. It took a while for Blood to calm down enough to listen to Sans. It took even longer for Sans to convince Blood to let him help through the rest of his heat. They decided to continue, right after they got a bath and ate something.

**Author's Note:**

> I hope you all enjoyed! Thank you for reading! Don't be afraid to tell me what you think in a comment!
> 
> If you would like a say in what I make next, check out my Twitter. You MUST have your BIRTHYEAR public in order to follow me. if you do not, you will be BLOCKED with no hope of ever being unblocked. My Twitter is @sxh1417.


End file.
